Author Topic: Top end run. (Read 9428 times)

andrewsw · « **on:** September 08, 2006, 09:32:45 PM »

I got a chance to do some top end runs and want to get some comparisons from others before I start swapping jets

I've a '93 B4 with a Yosh full exhaust, k&n filter, stock airbox with snorkel removed, 97.5 mains (not 100 as I thought previously). This is a fully naked bike with my 6'1" 200#'s tucked in as tight as I could get. Everything else is in decent shape: valves recently (300 miles) adjusted, sync is pretty close but a little off from some recent carb work, etc.

So wide open on a flat road with not much wind, but a very hot 94 F, I hit 108 indicated on successive runs with just a little vvvveeeerrrryyyyy slow pull left like it might have gone to 110 absolute top. Up above 100 (about 10k on the revs) it was just about out of pull and really crawled its way up from that point on.

I suspect I should be able to get more top than that. Am I right on this? or should I be happy? I have a few mains floating around (102.5 and 105, but no 100's) that I could try.

I have no indication that I am running lean (popping for example) but haven't done a throttle chop to check the plugs and see for sure.

Coopz · « **Reply #1 on:** September 08, 2006, 10:10:27 PM »

I have had 128ish indicated on my '92 B4. But I do have a fairing, and i'm not quite 6'1"! lol

I'd say that 108 is quite respectable, but you should be able to get a bit more out of it.

I dont know what you are talking about when you talk about 100 mains, so i'll just ignore that bit! lol

gsxr400 racer · « **Reply #2 on:** September 08, 2006, 10:11:36 PM »

how many wires to the plugs on the cdi the small plug mainly?

Krautwagen · « **Reply #3 on:** September 08, 2006, 11:27:09 PM »

Only once did I do it, but I was able to hit ~115mph with those carbs. I weigh ~160, so your 110 sounds to be about right.

interfuse · « **Reply #4 on:** September 08, 2006, 11:39:21 PM »

You should be able to go faster then that! I've had an indicated 200+ kph (125mph)... mind you i'm pretty much weightless (5'11", 135 lbs)!

...and the speedo is optimistic.

Farre · « **Reply #5 on:** September 09, 2006, 09:01:05 AM »

Quote

You should be able to go faster then that! I've had an indicated 200+ kph (125mph)... mind you i'm pretty much weightless (5'11", 135 lbs)! Laughing ...and the speedo is optimistic.

+1!

Yesterday i had a chance to whop the throttle, and got a constant 190kmh, and this was with a pillion hunched up behind me.
i'm guessing our weights combined around the 120kg's so equals 240pounds?

andrewsw · « **Reply #6 on:** September 09, 2006, 12:45:21 PM »

[quotehow many wires to the plugs on the cdi the small plug mainly?[/quote]

not sure, but I'll check and report back. you're thinking of a limiter I assume?

I'm pretty sure it was a horsepower issue. I think my power is peaking around 10k and falling off rapidly after that. I had similar behavior in 5th gear where after about 10k, its pull really dropped dramatically, and I would shift into six which dropped the revs back into the power and got me up over 100. So something is going on with the power band there.

I'll report back on the CDI.

andrewsw · « **Reply #7 on:** September 09, 2006, 12:51:02 PM »

Krautwagen, I agree that if you were getting 115 at your weight, it reasonable that I might only get 110. And of course, there are a lot of other factors that I haven't looked into that could affect things as well -- namely engine wear. If you throw in the altitude difference, which is probably not enough to need rejetting, but is still probably a factor in peak horsepower, then it really makes sense.

I still think it should be pulling better at that point though. Did you experiment with the main jets at all? the guys at FP seemed to think its a borderline case for the main jet with the k&n etc.

I've gotta do a throttle chop (ugh, pulling hot plugs is scary) and see what she's doing up there.

Thief400 · « **Reply #8 on:** September 09, 2006, 02:40:27 PM »

With mine I hit over 220 kph and start hitting the rev limiter and yes i have stock gearing before anyone asks. And I'm a heavy weight 210 without my leathers on. Yours Is also a 93 and they have a lot tamer valve timing so that might be all she has

andrewsw · « **Reply #9 on:** September 09, 2006, 03:14:56 PM »

Quote

Yours Is also a 93 and they have a lot tamer valve timing so that might be all she has

huh. thats interesting to learn. that probably explains the difference in the valve clearances too. is it as simple as putting the older cams in? or is there more to it than that? not something I'd likely do, but I'm curious.

A

Thief400 · « **Reply #10 on:** September 09, 2006, 04:52:26 PM »

Yes Jay maybe able to hook you up with some hotter cams

r_outsider · « **Reply #11 on:** September 09, 2006, 05:20:10 PM »

Quote from: interfuse

You should be able to go faster then that! I've had an indicated 200+ kph (125mph)... mind you i'm pretty much weightless (5'11", 135 lbs)! ...and the speedo is optimistic.

That's probably not helping with your insurance...

gsxr400 racer · « **Reply #12 on:** September 09, 2006, 11:33:46 PM »

you bike is a 93 ? lmao check the cdi wires

interfuse · « **Reply #13 on:** September 10, 2006, 01:10:57 AM »

Quote

That's probably not helping with your insurance...

It's not my fault I'm skinny.

Seriously, don't get caught doing double the limit on the street. And if you do don't stop.

Coopz · « **Reply #14 on:** September 10, 2006, 07:02:12 PM »

I hate CDI

It sounds wierd that the power drops dramatically after 10k revs. And that when you go up a gear you get into the power. My engine* pulls well till about 8k, and then it pulls like a train, ans then at about 10k it's off like a rocket! Sounds like yours is the exact opposite. And when i want to get into the power (for overtaking or whatever) I drop a gear, i dont go up a gear.

*This was before it blew up.

This makes me agree with Jay in thinking that it must be the CDI. The CDI controls how the engine behaves. (After getting a new engine, i discovered that my CDI is phucked and the engine wont rev at all!)

Check the wires coming out of the CDI, and check them where they go into the coils / engine (wherever the hell they go!). If these are okay, there is a company (at least one i know of in the UK) who test them for about £30, and if they find a fault they can fix it for £90-120. Alternatively, you could buy one online, like on eBay, or even on here, I have seen a couple advertised lately. I bought one off ebay last week for £40, but I seen one at £250, so there is a huge price range. The last option is that you could fix it yourself. There are a few posts that detail how to do this, but they are dotted all over te place and a bit vague and confusing. This is a post i made with all of the information I found about DIY CDI repair, and a few peoples helpful comments. If you'd be interested in fixing it yourself, take a look:
http://forums.banditalley.net/viewtopic.php?p=51122&highlight=#51122

That is all assuming that it is your CDI thats busted. If thats not the problem, then I can't help! Sorry!